COVID-19NCT05650905
Retinal Neurovascular Coupling in Patients Previously Infected With COVID-19
An observational study of COVID-19 and Post-COVID-19 Syndrome, run by Medical University of Vienna at 1 site in Austria.
Trial summary
The Study objective is to measure retinal neurovascular coupling and blood flow parameters in patients previously infected with COVID-19, long COVID-19 and healthy age- and sex- matched control subjects Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- COVID-19, Post-COVID-19 Syndrome
- What is being tested?
- Dynamic Vessel Analyzer (DVA), Fourier domain optical coherence tomography (FDOCT) and Optical coherence tomography (OCT)
- Type of treatment
- Medical device
- How many people
- 90 participants
- Where
- 1 siteAustria
- Study dates
- 26 Jul 2021to 31 Dec 2025
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: A total of 90 subjects will be included: 30 subjects previously infected with COVID-19 30 subjects with long COVID-19 30 age-and sex- matched subjects with no history of COVID-19 infection
Who may be able to join
- Men and women aged over 18 years
- Non-smokers
- Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant
- No previous history of COVID-19 infection
- Negative testing for SARS-CoV-2 seroprevalence using nucleocapsid antibody tests
- Negative PCR test for SARS-CoV-2
Show all 19Show fewer
- Normal ophthalmic findings, ametropy < 6 Dpt.
- Inclusion criteria for subjects with history of COVID-19 infection
- Men and women aged over 18 years
- Non-smokers
- History of COVID-19 infection (confirmed by a positive PCR test for SARS-CoV2 in the medical history) within the last 6 months
- Positive testing for SARS-CoV-2 seroprevalence using spike protein IgG antibody tests
- Negative PCR test for SARS-CoV-2
- Men and women aged over 18 years
- Non-smokers
- History of COVID-19 infection (confirmed by a positive PCR test for SARS-CoV2 in the medical history)
- Positive testing for SARS-CoV-2 seroprevalence
- Negative PCR test for SARS-CoV-2
- Long Covid according to the latest WHO-Guidelines
Who cannot join
- Any of the following will exclude a healthy control subject from the study:
- Symptoms of a clinically relevant illness in the 3 weeks before the first study day
- Presence or history of a severe medical condition as judged by the clinical investigator
- Participation in a clinical trial in the 3 weeks preceding the study
- Blood donation during the previous three weeks
- History or family history of epilepsy
Show all 27Show fewer
- Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator
- Best corrected visual acuity < 0.8 Snellen
- Pregnancy, planned pregnancy or lactatin
- History of epilepsia
- Any of the following will exclude a subject with history of COVID-19 infection from the study:
- Blood donation during the previous three weeks
- History or family history of epilepsy
- Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator
- Best corrected visual acuity < 0.8 Snellen
- Ametropy >6 Dpt
- Pregnancy, planned pregnancy or lactating
- History of epilepsia
- Any of the following will exclude a subject with long COVID-19 from the study:
- Blood donation during the previous three weeks
- History or family history of epilepsy
- Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator
- Best corrected visual acuity < 0.8 Snellen
- Ametropy >6 Dpt
- Pregnancy, planned pregnancy or lactating
- History of epilepsia
- Diabetes mellitus
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Austria1 site, 1 recruiting
- Recruiting
Medical University of Vienna, Department of Clinical Pharmacology
Vienna, State of Vienna, 1090
Doreen Schmidl, MD, PhD, 0043140400 ext. 29810, klin-pharmakologie@meduniwien.ac.at
Doreen Schmidl, MD, PhD
About this study
The Study objective is to measure retinal neurovascular coupling and blood flow parameters in patients previously infected with COVID-19, long COVID-19 and healthy age- and sex- matched control subjects
Read the detailed description
The coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is affecting almost all countries in the world and because of its worldwide spread has been declared as pandemic in March 2020. While respiratory symptoms are the main manifestation of acute infection, there is also increasing evidence that neurological and vascular symptoms occur, and it is unknown whether residuals remain after patients have recovered. A recent report shows that changes in the human retina are even present one month after onset of symptoms. The eye, as an extension of the brain, offers the advantage that blood vessels as well as neural tissue can be visualized non-invasively in-vivo. Neurovascular coupling is the ability of neural tissue to adapt its blood flow to its metabolic demands, a phenomenon that does not only occur in the brain, but also in the retina. In the retina, neurovascular coupling can be studied by stimulating the retina with flicker light and measuring the response of the vessels. Retinal neurovascular coupling has been found to be impaired in diseases of the central nervous system (CNS) as well as in diseases associated with endothelial dysfunction. Since COVID-19 comes with CNS manifestations as well as endothelial dysfunction, we speculate that retinal neurovascular coupling might be impaired in patients even after they have recovered from COVID-19 infection. In the current study, retinal neurovascular coupling will be measured in patients who have recovered from COVID-19 infection with and without long COVID-19 and in healthy age- and sex-matched controls with no history of COVID-19 infection. In addition, retinal oxygen saturation, vessel diameters, vessel density as well as retinal and optic nerve head blood flow will be measured. To assess structural changes, measurement of central retinal thickness as well as retinal nerve fiber layer thickness will be performed.
- Conditions
- COVID-19, Post-COVID-19 Syndrome
- Being tested
- Dynamic Vessel Analyzer (DVA), Fourier domain optical coherence tomography (FDOCT), Optical coherence tomography (OCT), Laser Speckle Flowgraphy (LSFG), Proteomics and Metabolites in Plasma, tear fluid and finger sweat
- Medical subject headings
- COVID-19, Post-Acute COVID-19 Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Dynamic Vessel Analyzer (DVA)Device
Retinal neurovascular coupling, Retinal vessel diameters and Retinal oxygen saturation will be assessed using the DVA
Fourier domain optical coherence tomography (FDOCT)Device
Retinal blood velocities and Retinal blood flow will be assessed using the FDOCT
Optical coherence tomography (OCT)Device
Retinal nerve fiber layer thickness, Central retinal thickness and Retinal vessel density will be assessed using the OCT
Laser Speckle Flowgraphy (LSFG)Device
Normalized blur and Relative flow volume will be assessed using the LSFG
Proteomics and Metabolites in Plasma, tear fluid and finger sweatDiagnostic test
Proteomics and Metabolites in Plasma, tear fluid and finger sweat will be assessed using a Blooddraw, filter paper and Schirmer-test
| Study group | Role | What they receive |
|---|---|---|
| subjects previously infected with COVID-19 | subjects previously infected with COVID-19 Receives: Device: Dynamic Vessel Analyzer (DVA); Device: Fourier domain optical coherence tomography (FDOCT); Device: Optical coherence tomography (OCT); Device: Laser Speckle Flowgraphy (LSFG); Diagnostic Test: Proteomics and Metabolites in Plasma, tear fluid and finger sweat | |
| subjects with long COVID-19 | subjects with long COVID-19 according to the WHO-guideline Receives: Device: Dynamic Vessel Analyzer (DVA); Device: Fourier domain optical coherence tomography (FDOCT); Device: Optical coherence tomography (OCT); Device: Laser Speckle Flowgraphy (LSFG); Diagnostic Test: Proteomics and Metabolites in Plasma, tear fluid and finger sweat | |
| healthy age-and sex- matched control subjects with no history of COVID-19 infection | healthy age-and sex- matched control subjects with no history of COVID-19 infection Receives: Device: Dynamic Vessel Analyzer (DVA); Device: Fourier domain optical coherence tomography (FDOCT); Device: Optical coherence tomography (OCT); Device: Laser Speckle Flowgraphy (LSFG); Diagnostic Test: Proteomics and Metabolites in Plasma, tear fluid and finger sweat |
What is being measured
The primary outcome is the main question the study is designed to answer.
Retinal neurovascular coupling
Retinal neurovascular coupling will be assessed using the DVA
Measured: Day 0
Secondary outcomes (13)
Retinal vessel diameters
Retinal vessel diameters will be assessed using the DVA
Measured: Day 0
Retinal oxygen saturation
Retinal oxygen saturation will be assessed using the DVA
Measured: Day 0
Retinal blood velocities
Retinal blood velocities will be assessed using FDOCT
Measured: Day 0
Retinal blood flow
Retinal blood flow will be assessed using FDOCT
Measured: Day 0
Ocular perfusion pressure
Ocular perfusion pressure is going to be calulated
Measured: Day 0
Retinal nerve fiber layer thickness
Retinal nerve fiber layer thickness will be assessed using OCT
Measured: Day 0
Central retinal thickness
Central retinal thickness will be assessed using OCT
Measured: Day 0
Retinal vessel density
Retinal vessel density will be assessed using OCT
Measured: Day 0
Normalized blur
Normalized blur will be assessed using LSFG
Measured: Day 0
Relative flow volume
Relative flow volume will be assessed using LSFG
Measured: Day 0
Proteomics and Metabolites in Plasma
Proteomics and Metabolites in Plasma will be assessed through a Blood Sample
Measured: Day -14 to -1
Proteomics and Metabolites in tear fluid
Proteomics and Metabolites in tear fluid will be assessed using Schirmer
Measured: Day 0
Proteomics and Metabolites in finger sweat
Proteomics and Metabolites in finger sweat will be assessed using finger sweat filters
Measured: Day 0
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Dec 2022
- Study start26 Jul 2021
- Primary completion31 Dec 2025 (estimated)
- Study completion31 Dec 2025 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for COVID-19Studies of the same condition, open and under way.
- More trials run by Medical University of ViennaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Cross-sectional
- Enrolment
- 90 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Medical University of Vienna
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Doreen Schmidl, Medical University of Vienna
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05650905
- Sponsor's protocol ID
- OPHT-180520
- Status last verified
- Dec 2024
- First submitted
- 13 Dec 2022
- Last updated
- 16 May 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Pai V, Bileck A, Hommer N, Janku P, Lindner T, Kauer V, Rumpf B, Haslacher H, Hagn G, Meier-Menches SM, Schmetterer L, Schmidl D, Gerner C, Garhofer G. Impaired retinal oxygen metabolism and perfusion are accompanied by plasma protein and lipid alterations in recovered COVID-19 patients. Sci Rep. 2024 Apr 10;14(1):8395. doi: 10.1038/s41598-024-56834-4.
PubMed 38600099
Study at a glance
From the registry record, last updated by the sponsor on 16 May 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Retinal Neurovascular Coupling in Patients Previously Infected With COVID-19
- ClinicalTrials.gov ID
- NCT05650905
- Acronym / sponsor ID
- OPHT-180520
- Conditions
- COVID-19, Post-COVID-19 Syndrome
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 90 participants (estimated)
- Lead sponsor
- Medical University of ViennaUniversity, hospital or other
- Study start
- 26 Jul 2021 (actual)
- Primary completion
- 31 Dec 2025 (estimated)
- Study completion
- 31 Dec 2025 (estimated)
- First posted
- 14 Dec 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The Study objective is to measure retinal neurovascular coupling and blood flow parameters in patients previously infected with COVID-19, long COVID-19 and healthy age- and sex- matched control subjects
Detailed description
The coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is affecting almost all countries in the world and because of its worldwide spread has been declared as pandemic in March 2020. While respiratory symptoms are the main manifestation of acute infection, there is also increasing evidence that neurological and vascular symptoms occur, and it is unknown whether residuals remain after patients have recovered. A recent report shows that changes in the human retina are even present one month after onset of symptoms. The eye, as an extension of the brain, offers the advantage that blood vessels as well as neural tissue can be visualized non-invasively in-vivo. Neurovascular coupling is the ability of neural tissue to adapt its blood flow to its metabolic demands, a phenomenon that does not only occur in the brain, but also in the retina. In the retina, neurovascular coupling can be studied by stimulating the retina with flicker light and measuring the response of the vessels. Retinal neurovascular coupling has been found to be impaired in diseases of the central nervous system (CNS) as well as in diseases associated with endothelial dysfunction. Since COVID-19 comes with CNS manifestations as well as endothelial dysfunction, we speculate that retinal neurovascular coupling might be impaired in patients even after they have recovered from COVID-19 infection. In the current study, retinal neurovascular coupling will be measured in patients who have recovered from COVID-19 infection with and without long COVID-19 and in healthy age- and sex-matched controls with no history of COVID-19 infection. In addition, retinal oxygen saturation, vessel diameters, vessel density as well as retinal and optic nerve head blood flow will be measured. To assess structural changes, measurement of central retinal thickness as well as retinal nerve fiber layer thickness will be performed.
Study design
- Observational model
- Case-control
- Time perspective
- Cross-sectional
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| subjects previously infected with COVID-19 | – | Device: Dynamic Vessel Analyzer (DVA), Device: Fourier domain optical coherence tomography (FDOCT), Device: Optical coherence tomography (OCT), Device: Laser Speckle Flowgraphy (LSFG), Diagnostic Test: Proteomics and Metabolites in Plasma, tear fluid and finger sweatsubjects previously infected with COVID-19 |
| subjects with long COVID-19 | – | Device: Dynamic Vessel Analyzer (DVA), Device: Fourier domain optical coherence tomography (FDOCT), Device: Optical coherence tomography (OCT), Device: Laser Speckle Flowgraphy (LSFG), Diagnostic Test: Proteomics and Metabolites in Plasma, tear fluid and finger sweatsubjects with long COVID-19 according to the WHO-guideline |
| healthy age-and sex- matched control subjects with no history of COVID-19 infection | – | Device: Dynamic Vessel Analyzer (DVA), Device: Fourier domain optical coherence tomography (FDOCT), Device: Optical coherence tomography (OCT), Device: Laser Speckle Flowgraphy (LSFG), Diagnostic Test: Proteomics and Metabolites in Plasma, tear fluid and finger sweathealthy age-and sex- matched control subjects with no history of COVID-19 infection |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- A total of 90 subjects will be included: 30 subjects previously infected with COVID-19 30 subjects with long COVID-19 30 age-and sex- matched subjects with no history of COVID-19 infection
Key inclusion criteria (19 listed)
- Men and women aged over 18 years
- Non-smokers
- Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant
- No previous history of COVID-19 infection
- Negative testing for SARS-CoV-2 seroprevalence using nucleocapsid antibody tests
Key exclusion criteria (27 listed)
- Symptoms of a clinically relevant illness in the 3 weeks before the first study day
- Presence or history of a severe medical condition as judged by the clinical investigator
- Participation in a clinical trial in the 3 weeks preceding the study
- Blood donation during the previous three weeks
- History or family history of epilepsy
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Dynamic Vessel Analyzer (DVA)Retinal neurovascular coupling, Retinal vessel diameters and Retinal oxygen saturation will be assessed using the DVA | Device | healthy age-and sex- matched control subjects with no history of COVID-19 infection, subjects previously infected with COVID-19, subjects with long COVID-19 |
| Fourier domain optical coherence tomography (FDOCT)Retinal blood velocities and Retinal blood flow will be assessed using the FDOCT | Device | healthy age-and sex- matched control subjects with no history of COVID-19 infection, subjects previously infected with COVID-19, subjects with long COVID-19 |
| Optical coherence tomography (OCT)Retinal nerve fiber layer thickness, Central retinal thickness and Retinal vessel density will be assessed using the OCT | Device | healthy age-and sex- matched control subjects with no history of COVID-19 infection, subjects previously infected with COVID-19, subjects with long COVID-19 |
| Laser Speckle Flowgraphy (LSFG)Normalized blur and Relative flow volume will be assessed using the LSFG | Device | healthy age-and sex- matched control subjects with no history of COVID-19 infection, subjects previously infected with COVID-19, subjects with long COVID-19 |
| Proteomics and Metabolites in Plasma, tear fluid and finger sweatProteomics and Metabolites in Plasma, tear fluid and finger sweat will be assessed using a Blooddraw, filter paper and Schirmer-test | Diagnostic test | healthy age-and sex- matched control subjects with no history of COVID-19 infection, subjects previously infected with COVID-19, subjects with long COVID-19 |
Primary outcome
Retinal neurovascular coupling
Time frame: Day 0
Retinal neurovascular coupling will be assessed using the DVA
13 secondary outcomes
Retinal vessel diameters
Time frame: Day 0
Retinal oxygen saturation
Time frame: Day 0
Retinal blood velocities
Time frame: Day 0
Retinal blood flow
Time frame: Day 0
Ocular perfusion pressure
Time frame: Day 0
Retinal nerve fiber layer thickness
Time frame: Day 0
Central retinal thickness
Time frame: Day 0
Retinal vessel density
Time frame: Day 0
Normalized blur
Time frame: Day 0
Relative flow volume
Time frame: Day 0
Proteomics and Metabolites in Plasma
Time frame: Day -14 to -1
Proteomics and Metabolites in tear fluid
Time frame: Day 0
Proteomics and Metabolites in finger sweat
Time frame: Day 0
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 May 2025.
- Derived from this study: PubMed 38600099Pai V, Bileck A, Hommer N, Janku P, Lindner T, Kauer V, Rumpf B, Haslacher H, Hagn G, Meier-Menches SM, Schmetterer L, Schmidl D, Gerner C, Garhofer G. Impaired retinal oxygen metabolism and perfusion are accompanied by plasma protein and lipid alterations in recovered COVID-19 patients. Sci Rep. 2024 Apr 10;14(1):8395. doi: 10.1038/s41598-024-56834-4.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Medical University of Vienna, Department of Clinical Pharmacology
Vienna, Austria
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of COVID-19 and Post-COVID-19 Syndrome, run by Medical University of Vienna at 1 site in Austria.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 19 inclusion and 27 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 16 May 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Austria. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Retinal neurovascular coupling (time frame: Day 0). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05650905, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 May 2025.